The present invention relates to transdermal (transcutaneous) drug applicators and methods of their use, as well as to a drug-containing medium for use with such applicators, and more particularly to iontophoretic drug applicators which are electrically operated and which exhibit properties which facilitate the transcutaneous delivery or transfer of drugs, and the like.
Iontophoresis has come into increasing attention as an effective method for the topical application of drugs through the skin to exert a systemic effect.
Iontophoresis is the technique of delivering ionic, ionizable or polar drugs through a person's skin, by placing a solution or other medium containing the ions, ionizable or polar substances in contact with the skin, and applying electric current to the medium. The medium containing the ions, ionizable or polar substance may be a fluid or a solid and is in contact with a first electrode. Ions are caused to migrate from the medium through the skin or tissue by the application of electric current from the first electrode, to the medium and then to a second electrode spaced from the first electrode.
Iontophoretic devices have been designed so that one electrode is in contact with the medium containing the drug of like charge to that of the electrode, while the second electrode is in contact with a medium lacking such drug. Alternatively, the second electrode can be in contact with a different drug having a charge the same as that of the second electrode.
In addition, iontophoretic devices have been proposed containing pulsing means, namely means for effecting depolarization of the electrodes at spaced intervals, in an attempt to lower the voltage needed for the iontophoresis.
The overall size of the iontophoretic device should desirably be minimized for cost effectiveness and aesthetics, and the dosage capability maximized.
It is an object of the present invention to provide improved iontophoretic devices comprising two electrodes insulated from each other, that is minimum in size and capable of maximum drug delivery, and yet reasonable in cost.
It is a further object of the present invention to provide an improved iontophoretic system utilizing improved electrode construction, which permits delivery of a single drug through both electrodes, by use of a means to reverse the polarity of the two electrodes. The means for reversing the polarity of the two electrodes can be an electronic switching device, which can optionally be coupled to a pulse generating device. The pulse generating device permits the delivery of electrical current in pulses, which, in cooperation with the electronic switching device, can be timed to reverse the polarity of the electrodes at spaced intervals related to the pulses, or independent of the pulses. Still another object of this invention is an iontophoretic device having means to vary the amount of current delivered to the device.
Another object of this invention is the provision of a drug-containing medium for use in the iontophoretic device, which layer is backed on both sides with a pressure sensitive adhesive.
These and other objects and advantages of the invention, will become more apparent from a reading of the following detailed description of the preferred modifications and embodiments of the invention.